Centrifugal metal-pipe mold



March 4 1924.'

'J. B. LADD CENTRIFUGAL METAL PIPE MOLD Filed July 12, 1.922

ATTORNEY Patented Mar.4,1924. v

UNITED STATES PATENT OFFICE.

JAMES 13. mm), or ARDMORE, PENNSYLVANIA, nssrenon r UNITED s'm'rns' cAs-r IRON PIPE & FOUNDRY COMPANY, OF BURLINGTON, NEW JERSEY, A. CORPORA TION OF NEW JERSEY.

QEN'I'BIFUGAI' METAL-PIPE MOLD.

Application filed July 12, 1922. Serial No. 574,489.

To all whom it may concern:

Be it known'that I, JAMES B. Lam), a citizen of the United States of America, and resident of Ardmore, in the county of Montgomery, in the State of Pennsylvania, have invented a certain new and useful Improvement in Centrifugal Metal-Pipe Molds, of which the following is a true and exact description, reference being had to the accompanying drawings, which form a part thereof.

My invention relates to the construction of metal pipe molds used in the manufacture of centrifugally cast pipe and, in ordinary practice, cooled by water in contact with their outer surfaces. In the use of such molds, which are longjand relatively narrow, they have been very generally enlarged at one end so as to provide for the formation of a bell end on the pipe. The exterior of the'mold is maintained at a low temperature, generally somewhere below 200 F. While the interior of the mold, which is in contact with the melted metal poured into the mold to form the casting, is normally heated to a quite high temperature so that the interior portion of the mold tends to expand but is restrained by the cool exterior portion of the mold. Obviously, therefore, during the pouring of the metal, the interior of the mold will be compressed by this expansive action and this compression ma well be beyond the elastic limit of the meta Again, after the casting is made and after it is withdrawn from the mold, the interior portion of the mold, of course, is cooled and tends to contract, and this contraction is also resisted by the 0001 exterior of the metal mold. Obviously, the strains to which the metal is exposed, for the reasons above stated, operate both circumferentially and longitudinally and it has been found in practice that these strains have a tendency to destroy the smooth interior surface of the mold so that it becomes more or less-rough I tractive strains to roufihen the inside of the mold and Iv accomplis this by cutting narrow slots or rooves inthe inside of the mold so as to divi e the inner surface of the mold 1nto separate segments, in which segments the metal can expand and contract wlth approxlmate freedom and without exerting destructive strains on the mold surface. The

slots must be so narrow that the melted metal poured 1nto the mold will not penetrate lnto them even under the considerable pressure due to'the rapid rotation of the centrifugal mold. At the same time the slots should be sufliciently broad, and should divide the inner surface of the mold into segments of such size, that these segments can expand and contract freely. The slots are of such dimensions that the 'chillin effect of the cooled metal on the mold w1ll prevent the entry of'the fused metal into the slots.

The slots should be from one hundredth to two hundredths of an inch wide according to the dtemperature and nature of the'fiuid metal use Referring now to the drawings in which my invention is illustrated.

Figure 1 is a lon itudinal section of a centrifugal pipe mol constructed in accordance with my invention.

Fi ure 2 is across section through such a mo d shown on an enlarged scale.

Figure 3 is a view of a segment of the mold shown on a still larger scale.

Figure 4 is a face view of a segment of the inside of the mold shown on a scale etc. are circumferential narrow slots intersecting the lon 'tudinal slots, as best shown 1n Flg. 4. In ig. 1, only one of the longitudinal slots is shown but it will be undermerges into the enlarged ortion indicated.

at A and ordinarily 1t W1 form a mold with only longitudinal slots, although circumferential slots are desirable of h' Havin what-.1 c aim as new and desire to secure by be suficient to but would add considerably to the cost of manufacture: It will be obvious that in place of making the circumferential slots separate from and arallel to each other they can be made ical form, as indicated at E, in Fig. 5. now described my invention,

Letters Patent, is:

and relatively narrow centrifl (pipe mold having its 1nner 1. A lon ugal metal ic surface divide grooves which are too narrow to permit the Masses into separated segments by narrow slots or grooves WhlCh are too nar-.,

fluid metal for the pipe cast' to enter under the conditions 0 use and w ich diminish the strains caused by the alternate heating and cooling of the inner portions of the mold. .12"

3. A lon and relatively narrow centrifugal meta ic pipe mold in the form of a cylinder with one end enlargedto form the bell end of a pipe having its inner surface adjacent to the oint' where the mold enlarges into the be 1 formed with narrow slots or grooves too narrow. to ermit the inflow of melted metal under con itions of use and whereby the strains caused by expansion and contraction of the inner portions of the mold are diminished.

4. A centrifugal long and relatively narrow metallic pipe mold having its inner surface divided into separated segments by narrow slots or grooves running both longitudinally and circumferentially which are too narrow to 'permit the fluid metal for the pipe casting to enter under the conditions of use and which diminish the strains caused by the alternate heating and cooling of the inner portion of the mold.

' JS B. LADD. 

